Posted
by
kdawson
on Tuesday September 19, 2006 @02:02PM
from the is-that-a-quarter-in-your-pocket? dept.

Krishna Dagli writes, "MIT researchers are putting a tiny gas-turbine engine inside a silicon chip about the size of a quarter. The resulting device could run 10 times longer than a battery of the same weight, powering laptops, cell phones, radios, and other electronic devices." From the article: "All the parts work. We're now trying to get them all to work on the same day on the same lab bench." The goal is to do that by the end of the year.

Since the mass of these materials is super small, the fact that they are moving at high velocity is no cause to hide under one's bed.Also, at 20,000 rpm.. assuming that the "revolution" is a distance of 1 or 2 millimeters.. the ACTUAL velocity is nothing to send a letter home with.

Do the math (remember we are talking about the speed of the part of the object that is actually moving).

Another way of looking at it.. the total force cannot exceed the energy output of the gas expansion.. which is the result

Mass should be small since mass/volume hase cubing scaling. I expect MIT is not too concerned about it since they did not mention it.

I used to work at Cummins research center -- watch a turbocharger burst test if you get the chance, basically dump in as much fuel/air as it takes to get the flywheel to fly apart. Test is: is the casing is strong enough to contain all the flying pieces.

I saw a documentary on the development of the Airbus 380... they showed the blade failure test for the engines. Same problem. They ran the engine up to full speed then detached one of the turbine blades. Big noise but the engine housing held all of the debris... amazing.

Also, at 20,000 rpm.. assuming that the "revolution" is a distance of 1 or 2 millimeters.. the ACTUAL velocity is nothing to send a letter home with.

TFA said it runs at 20 krps, which would be 1.2 million rpm. Even if the mass is low, do you really want to be around when the compressor and/or turbine blades come apart? Historically, compressor disintegration [google.com] has been a Bad Thing.

Well according to another article the turbine is 4mm in diameter, so google says.5 * 4mm * pi * 20000 is about 125.6 meters. 125 meters per second is about the velocity of a low end bb gun. Given my adolecent expirimentation in terminal ballistics, a similar low end bb gun will barely penetrate both sides of a soda can. It should be a simple matter to provide the engine with a scatter shield stronger than a soda can.

Lasers and turbines on chips?
I think this is an elaborate plan to make deadly military level pc components.
With the detection of non-drm'd media, the chip will eject, fly close to you and shoot you in the face.
It's the next level after "Trusted Computing", "Feared Computing".

No, but I did think it was a PITA having to quickly plug into a wall socket as my laptop's about to put itself to sleep when the battery's getting low... now I'm gonna have to jump in the car to buy some fuel! I could syphon out of the car, but that's a bad habit to get into, which could lead to me finding myself having to/cycle/ to get some fuel for the car/and/ the laptop!

Actually, since they're using a microcarburetor instead of a microfuel injector, I can see a whole new service industry coming from this: "Honey, I need to get some work done so I'm going down to the Internet Bar for a while". The same business could serve your Wi-Fi, your favorite microbrew, and run your laptop on shots of whiskey.

I guess instead of building a better battery it's build a better generator. I guess all that matters is the efficiency of the design. My question is obviously heat production, and probably not as important exhast gases. How clean will this device burn. How well will these gases coexist with heat, and ionization.

The article doesn't mention what happens to the hot exhaust after it passes through the turbine. Does this mean that have not tackled this problem yet? This could give a whole new meaning to the whole "laptop frying your balls".

The article doesn't mention what happens to the hot exhaust after it passes through the turbine. Does this mean that have not tackled this problem yet? This could give a whole new meaning to the whole "laptop frying your balls".

Well, more like air-popping, really, so at least they'll be low-fat. Which, I concede, will likely not be much of a comfort.

It also doesn't mention how to fuel the engine...what happens when it runs out of gas?

Also, shouldn't they be making these run on bio-diesel?

What will be interesting is trying to get a fueled laptop (and spare fuel containers) aboard a commercial airliner. I read something the other day about one of the airlines (Virgin?) banning Dell and Apple laptops due to the exploding/burning battery debacle. Can you see them letting you on board with flammable and potentially explosive fuels? I sure can't!

One thing that many people forget - mostly due to the impression given by hollywood - is that gasoline and diesel don't explode at the drop of a hat. But the liquid form doesn't ignite, it must first be vaporized and mixed with oxygen before you have something that will readily combust. If you had a closed container of fuel, and prevented oxygen from getting in, it would be pretty safe. Even when liquids were allowed on airplanes, there weren't many stories [possibly none - does someone know of any?] of terrorists using gasoline in a bomb, despite the fact that it is easier to get than explosives and readily concealed.

Even a gas tank, which gets filled with air as the gas is used, rarely explodes even in the most violent car crashes. Usually what happens is that the fuel gets sprayed everywhere and burns on the surface. An explosion wouldn't come from all the gas suddenly burning, as happens with a genuine explosive, but from the vapors in the tank combusting and causing the tank to rupture.

It has been forbidden, in the United States, to take liquids of any kind onto an airplane ever since the so-called "foiled terrorist plot" (another name for it would be "a bunch of guys bragging to each other how they would take down an airplane if they wanted to" since it never got anywhere near the level of "plot". But I digress).

That's a really interesting read (pancake analogy aside), although it sounds like the resulting device will be pretty fragile. A small grain of sand or a little dust buildup would cause complete failure. Large mechanical systems have the ability to power through minor problems like that, but such a small one will not really be suited for military field use, I imagine.

I have to wonder how efficient it will be. Two things drive the efficiency of a gas turbine. The heat differentials and that leakage between the blades or impeller and the housing.The leakage is going to be a real issue since it is a ratio between the disk size and the gap. Bigger engines mean a higher ratio. That is one of the reasons that BIG gas turbines are relatively efficient while small one suck fuel like there is no tomorrow.

I'm not sure that's entirely fair; there are lots of systems that don't much like getting dirt in them, but that's what filters are for. Compared to a horse, an internal-combustion engine probably seems like it's really prone to problems -- after all, a horse doesn't mind if there's some dirt in its feed, but put the same amount of dirt into a tank of gas and run it directly into an engine, and you'll probably have issues. Hence, fuel and oil filters.They're not unsolvable problems. I assume that actual pro

That sounds like what happened with the M-16 machine gun. It's a really nice gun, but it has really tight tollerances, and doesn't operate very well when it's dirty, and hence it requires lots of cleaning, or it tends to jam. The AK-47 on the other hand, operates pretty well even when it is dirty, which is nice in combat situations, since you don't want your gun jamming in the middle of a battle. For more information, check out the wikipedia article [wikipedia.org]

That's not entirely true anyway. The real problem (mentioned by the wiki article) is that the M16 was believed to be self-cleaning, and isn't. They didn't issue cleaning kits. If you clean the gun, it remains fairly reliable, and if you configure it properly, it can be more accurate than the AK, anyway. (The AK's first two rounds are pretty good, but it climbs heavily after that.) Of course, M16s are usually set up for tumble, so that the tiny.223 caliber rounds have more of a tendency to hit bones and bou

Like a battery, this is not something that is going to be recharged in the field.

That is bullshit. You can swap a battery out for another one; in some laptops there are multiple batteries so you can do it without even hibernating the unit first. Users will definitely want to refuel in the field, while the laptop is in use.

It's not an issue anyway. You use a porous single element filter in between the fuel fill and the fuel storage. Problem solved. This amazing technology appears in your butane lighte

OK, I can picture the gas microturbine, and I can picture how a fuel/combustion energy source can outpower an electochemical energy source. However, do we have the capacity to make a generator that small. After all, we have the rotary power, how do we convert that into electrical energy?

I would be more interested in a bioelectric power source, like electric eel cells fed with sucrose.

Any electric motor can conceivably be used as an electric generator with little modification, or in most cases no modification at all. Considering how small we can make electric motors I don't think this will be the issue.

RTFA- they've got a 10-Watt microgenerator already working! Plus, anything you can run of gasoline, with a little tweaking of the carbuerator, will run off of Whiskey. If this gets popular, I'm going to start looking for an old bar that has DSL access for an investment property.

you might want to keep in mind that high concentrations of ethanol is pretty corrosive. thus is will turn any rubbers or plastics, some of which are found in the fuel system, that aren't designed to withstand it into jelly.that's why flex-fuel vehicles a bit more expensive than ordinary gas ones. they need to replace the rubbers and plastics with either different, more expensive, rubbers and plastics or stainless steel or something else not affected by it.

OK, I can picture the gas microturbine, and I can picture how a fuel/combustion energy source can outpower an electochemical energy source. However, do we have the capacity to make a generator that small.

As usual, the answer is in TFA, and it is "Yes":

Turbine blades, made of low-defect, high-strength microfabricated materials, spin at 20,000 revolutions per second -- 100 times faster than those in jet engines. A mini-generator produces 10 watts of power. A little compressor raises the pressure of air in pre

we have the rotary power, how do we convert that into electrical energy

Let's see.... maybe put a magnet on the rotor and little coils of wire around the outside? The changing magnetic field will induce current in any nearby conductors. This part was figured out more then 100 years ago. After all the only new thing here is the size.

ha, ha ha. How many times the rookies in my dept have come to me excitedly and said, "Great news Boss, Got all the functions implemented and unit testing checked out ok. All I need to do is to put it together. Finished 90% of the code in just 10% of the time. Want to take a month off to chill out in Aruba!"

Then they spend 200% of the allotted time to make sure what they wrote in the first 10% interact with one another correctly.

Given all the issues with "liquids" and flaming laptop batteries, I doubt this will be allowed on aircraft. (We'll see if methanol fuel cells pass TSA muster). I guess that's just another example of the terrorists winning their goal of keeping people out of the 21st century.

A microturbine requires a completely new energy source; can you imagine plugging a butane canister into your portable? All turbines have physical issues around energy lost through heat; remember in a traditional engine only about 50% of fuel burned actually goes to perform work.

Plus, you won't be able to take a laptop powered this way into the “secure” area of an airport... (Of course, once there is a rumor of someone trying blow up a plane with a Sony-made laptop battery, you won't be able to do that with any other laptop, either.)

What does "traditional engine" mean? If you mean internal combustion, the most efficient ICE is only about 50% efficient, it's a diesel in a container ship the size of a house. Your automobile's engine is maybe 25% efficient.

We need to stop burning stuff for our energy. Sure, batteries store energy made by mostly burning coal and stuff, but there other options for generating electricity to fill those batteries that don't involve adding carbon. I wish these people focused their research towards these types of energy sources.

Simple, small gas engines in lawnmowers and scooters are far, far dirtier than in a large modern car engine that has extensive polution control systems even when you take into account how much more gas a car uses than a lawnmower.

So I can't imagine this thing will run very clean at all. Not much room to put in a catalytic converter or other cleaning methods.

I have to wonder what a hundred million of these things running will do to indoor air quality. I don't think I want a thousand of these inside my office building.

The main reason that lawnmower engines are so incredibly dirty is that they are two-stroke engines. Two-stroke engines are inherently evil -- they burn dirty and emit huge quantities of unburnt fuel -- but they have a higher power-to-weight ratio and therefore see use where a small, powerful engine is required. It has a lot more to do with the engine design than it does the size. As for the pollution controls in cars, don't forget that car engines have to deal with an incredibly wide range of ever-changing speeds and power requirements. It's quite difficult to build an efficient engine which operates across such a wide range of speeds, but a simple engine driving a generator can operate at precisely one speed with a fixed load and can therefore be optimized for its precise requirements.

Further. the researchers in TFA are not building a piston-driven engine at all, they are building a gas-turbine engine. While it's difficult to speculate on the efficiency at this point (the thing doesn't even exist!), I would expect it to be relatively clean.

From the linked article: "...the researchers used regular unleaded fuel in a typical four stroke, four horsepower lawn mower engine and found, after one hour, that the PAH emissions are similar to a modern gasoline powered car driving about 150 kilometers (93 miles)."

2-stroke lawn mower? I haven't seen one of those in ages. I think LawnBoy made two-stroke mowers for a long time, but I thought they were all 4-stroke nowadays. Now my chainsaw, leaf-blower, hedge-clipper and weed-trimmer, are a different story.

For non-gearheads: If you need to fill 'er up with a mix oil+gasoline, you got yerself a 2-stroke.

Because as we move to hybrid gas-electric vehicles, more and more mechanics are finding they need a degree in electronics just to be able to fix your car. So to level the playing field, we felt that electronics geeks should have to learn how to fix an engine too.

will they be putting tiny engines inside silicon*e* ? Just imagine, breasts that swing *themselves* even when the woman is standing still. It truly would be Utopia. Or Stepford. I always get those two confused.

When steam engines were invented and developed in England by Newcomen the science of thermodynamics was lagging the technology. The steam engines work obviously but they could not get scaled down versions of the steam engines to work at all in the lab. Mainly because real engines were made with cast iron but the lab models were made with brass and it conducted away the heat away too quickly. At this time a man named James Watt, an instrumentmaker by profession did lots of work on the lab models and made an improved steam engine by mainly making the steam condense outside the cylinder. Also he invented the Watts Governor to regulate the speed of the machine. The moral of the story is that, heat engines dont scale down as easily as electronics.

Fluids in general behave much more differently in microscopic quantities than in large bulk quantities. I expect to be lugging large batteries for some time to come.

[Steam engines prove] that heat engines dont scale down as easily as electronics.

Steam engines of the era you're discussing [cottontimes.co.uk] heated water in a big drum, just hot enough so it turned to steam, then cooled it just enough so it condensed back to hot water. Both stages (especially the second) were critically dependent on conduction. The heat engine in the example works by burning a fuel-air mix at the the melting point of steel apparantly, and doesn't bother condensing the result. I think the issues are diffe

Just what we need these days, not less but MORE dependence on fossil fuels. What idiots! Besides the obvious problem of trying to fuel something that small at the gas pump and then paying for it in fractions of a penny, what about the carbon dioxide emissions that conbustion engines produce? Aren't we going to be in for a lot of people with lots of headaches and brain damage from using a device like this? Even though it's so small, it's STILL emitting carbon dioxide which is known to cause the more serious cases of fatal death. I still get behind my roaring battle cry: SOLAR POWER IS WHERE IT'S AT FOLKS!!! The sun is an abundant energy source. Amp the solar panel production up so that they are 99.999% efficient, and you won't need any other source of energy anywhere on the planet. Combine that with electricity resevoirs that can hold a couple hundred gallons of electricity, and you have a clear winner. Thumbs down on this for sure.

You obviously have no idea what you're talking about. Cars emit carbon dioxide, otherwise where would the greenhouse gasses that the environmental wackos wring their wimpy little hands about come from? (Yes, I admit that the environmentalists are right about the coming nuclear winter caused by cars, but that doesn't make them right) And as far as the more serious cases of fatal death, I'm talking about the kind of death where someone actually dies. I don't know how I can make it any clearer to you. You

Assuming that the turbine produces 10 watts of power (got this from TFA) and is 30% efficient (not an unreasonable assumption) this would mean that the turbine produced 10 watts of work and a little more than 20 watts would be dissipated as heat - far less than a modern PC microprocessor.

Because getting the efficiency to be high on such a small stirling engine is basically impossible, and if you can't get that up, then you won't get any useful amount of power out of it anyway, so why bother.